1. Field of the Invention
The present invention generally relates to a field emission source technology, in particular, to a composite field emission source and a method of fabricating the same.
2. Description of Related Art
Display devices are playing an increasingly important role in people's daily life. Computers, TVs, mobile phones, PDAs, digital cameras etc., all transmit information by controlling display devices. Contrary to the conventional Cathode Ray Tube displays, the latest-generation panel displays are advantageous in that they are light, compact, and health-friendly.
Among various technologies for panel display devices, field emission displays (FED) boast not only great graphic qualities as found in conventional Cathode Ray Tube displays, but also high luminous efficiency, short response time, good display coordination performance, high brightness of more than 100 ftL, slim and light structure, wide viewing angle, broad range of working temperature, and high acting efficiency, contrary to Liquid Crystal Displays (LCD) which are problematic in narrow viewing angle, narrow working temperature range, and short response time. Besides, FEDs do not require backlight modules; they can provide superior brightness even when used in sunlight. Therefore, the current field emission displays has been regarded as a new display technology that is competitive against the LCD technology and even replace the LCD technology.
Recently, research in electric emitter of the FED trends mostly to carbon material, for example amorphous carbon film, diamond film, diamond-like carbon film, and carbon nanotube, and is mainly the carbon nanotube with low turn-on field of carbon nanotube. In addition, the carbon nanotube FED is self luminescent, so it can be applied to backlight source of the LCD or can serve as a flat panel light source.
However, the structure of the carbon nanotube cannot bear the high current and is easily to be burnt up, and when it is applied to screen printing process, field emission points of the carbon nanotube are disordered and dense, so it is difficult to control the emission current. Although in Taiwan patent application No. 95115215, the technology of fabricating the carbon nanotube by using radio frequency (RF) magnetron sputtering is provided to solve the problem that the carbon nanotube is easily to be burnt up due to over-high current, the turn-on field is still high.